Field of the Invention
The present disclosure relates to a voice coil motor, a coil block for voice coil motor, a method of manufacturing the coil block and a voice coil motor having the coil block.
Discussion of the Related Art
Recently, a small optical device such as a super-small digital camera on a mobile phone or a high resolution digital camera has been developed and is formed with an actuator for adjusting magnification and focus. The camera on the mobile phone or the digital camera recently employs an actuator such as a VCM (voice coil motor) on a wide range base.
The conventional super-small digital camera on the mobile phone is such that it is impossible to adjust a gap between an image sensor and lens, and a lens driving device such as a VCM for adjusting the gap between the image sensor and the lens has been developed to allow the super-small digital camera to capture an improved image.
The VCM is a motor that uses a force from a magnetic field generated by a magnet and a magnetic field generated by a coil block facing the magnet, such that the VCM is adequate in adjusting a gap between a lens and an image sensor in a camera module.
The VCM includes a cylindrical bobbin mounted therein with a lens, and a coil block wound with a coil at a periphery of the bobbin. A conventional VCM includes a cylindrical bobbin mounted therein with a lens, and a coil block wound with a coil at a periphery of the bobbin. The conventional VCM is formed in such a manner that the coil-wound cylindrical coil block is coupled to the bobbin or a coil is wound on the periphery of the bobbin.
In a case the coil is wound on the periphery of the bobbin to form the coil block, there is a limitation in winding the coil, because the coil must be wound in even layers by alternatively winding the coil from a peripheral bottom end to a peripheral upper end of the bobbin and from the peripheral upper end to the peripheral bottom end of the bobbin.
In a case the coil is wound in the even layers, problems arise that the wound coil is easily unraveled, and it is difficult to discern which line is a winding start line and which line is a winding end line. In order to enhance the performance of VCM, many researches are being waged to improve a magnet generating a magnetic field and a coil block generating a magnetic field that reacts to the magnetic field generated by the magnet.